Changes

* If you increase the resistance in the kidneys you contribute to increasing total peripheral resistance.  This helps to return blood pressure towards normal.  (Angiotensin 2 also has vasoconstrictive effects in other organs.)

* If you increase the resistance in the kidneys you contribute to increasing total peripheral resistance.  This helps to return blood pressure towards normal.  (Angiotensin 2 also has vasoconstrictive effects in other organs.)

* The kidneys can tolerate the reduced perfusion allowing blood to be prioritised to organs which need it like the brain and heart.

* The kidneys can tolerate the reduced perfusion allowing blood to be prioritised to organs which need it like the brain and heart.

* The constriction of the efferent arterioles also reduces hydrostatic pressure in the [[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Pressure in the Peritubular Capillaries| Peritubular Capillaries]] this increases reabsorption of water and salt thus helping to restore the ECF and thus helps to normalise blood pressure.

* The constriction of the efferent arterioles also reduces hydrostatic pressure in the [[The Formation of the Filtrate by the Glomerular Apparatus- Anatomy & Physiology#Pressure in the Peritubular Capillaries|peritubular capillaries]] this increases reabsorption of water and salt thus helping to restore the ECF and thus helps to normalise blood pressure.

* The amount of waste excreted is variable with GFR.  Thanks to the normalised GFR the excretion of waste products such as urea is maintained.

* The amount of waste excreted is variable with GFR.  Thanks to the normalised GFR the excretion of waste products such as urea is maintained.